[ntp:questions] chrony as a server

William Unruh unruh at invalid.ca
Mon Feb 23 21:23:35 UTC 2015


On 2015-02-23, Paul <tik-tok at bodosom.net> wrote:
> On Mon, Feb 23, 2015 at 12:53 PM, William Unruh <unruh at invalid.ca> wrote:
>
>> As Lichvar says with chrony
>> you periodically read your watch, or listen to radio, and set the time
>> and chrony figures out that you have a drift rate of about 30PPM and
>> corrects. Now you may not value that possibility, which is perfectly all
>> right, but some people might.
>>
>
> Seems like someone should do some unbiased research and determine just how
> long it takes to find  clock drift, say to 2 ppm, using chrony with manual
> corrections.  Finding a nice (efficient) method would be useful too.

manual corrections are probably good to 1 sec. to get 1 sec at 2ppm is
about 5 days per measurement or 10 days altogether. 

>
> With NTPd I might set the clock, wait a month check the time and create a
> drift file.

Yes, But as Lichvar said, having the program do the work for you is
easier. You could also measure offsets by hand and use adjtimex to
adjust the clock yourself and not use either chrony or ntpd. 


>
> Sometimes you have to examine a use case and conclude that it's poor return
> on investment.  I think trying to discpline an uncharaterized oscillator
> with a wristwatch is certainly marginal.

Up to you. The option is there for chrony. 



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